Pliers with self-adjusting toggle means



Aug. 29, 1961 R. ROMMEL ET AL PLIERS WITH SELF-ADJUSTING TOGGLE MEANS 4 Sheets-Sheet 1 Filed Aug. 19,

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Aug. 29, 1961 R. ROMMEL ET AL PLIERS WITH SELF-ADJUSTING TOGGLE MEANS Filed Aug. 19, 1959 4 Sheets-Sheet 3 w M M WA #m NNMNQ Q N Jnvenfo rs Aug. 29, 1961 R. ROMMEL ET AL FLIERS WITH SELF-ADJUSTING TOGGLE MEANS Filed Aug. 19, 1959 4 Sheets-Sheet 4 Jn enfors Qaiwg M- States The present invention relates topliers in which a toggle action locks the jaws in closed position.

Usually, pliers of this kind are pressed of sheet steel and provided with hardened steel jaws. One of the jaws is fixed on one of the arms, while the other jaw is hinged on the same arm and operated by means of apivotable handle.

It has already been proposed to support the pivotable handle, relative to the rigid arm, through means of a toggle lever arrangement in which the part of the lever projecting beyond the toggle joint forms a handle, while the free end of the other part of the toggle lever rests against an abutment which is adjustable on the rigid arm. These pliers are unwieldy insofar as both hands are necessary for their operation. The gripping power obtainable through means of thetoggle action is adjusted, according to the required opening of the pliers, by adjusting the toggle lever abutment on the rigid arm.

It is one object of the present invention to provide pliers which eliminate the aforementioned deficiencies and which enable the pliers to be operated by one hand only. It is another object of the present invention to provide pliers wherein the toggle lever abutment forms a brake member which is biased and supported on the rigid arm. The gripping power or closing pressure is variable by adjusting the operating angle -ofthe toggle lever, by means of a stop screw, for instance. Releasing of the brake member andthus automatic gripping of the 'jaws on the workpiece is obtained by means of a tension spring connecting the brake member with the rigid arm.

It is yet another object of the present invention to provide pliers, wherein the brake member consists of a guide on the rigid arm and a tiltable clamp sleeve, hinged on the end of the toggle lever and sliding on the guide. Conveniently, the guide is formed of a bar having a wedge-shaped cross section, while the clamp sleeve guide bore is formed accordingly to obtain a locking action between the surfaces of the bar and the wedge-shaped guide surfaces of the clamp sleeve. On the other hand, it is also possible to support the toggle lever arrangement provided on the pliers by any other type of a locking device, as for instance, by means of a wedgeor ball-type clamping device or the like, which automatically opens to one side. It is important, however, to have the brake member adapted in a manner to enable closing and opening of the pliers with one hand and to automatically obtain the predetermined gripping power upon closing of the pliers, regardless of the dimensions of the workpiece.

With these and other objects in view which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawings, in which:

FIGURE 1 is a side elevation of one embodiment of the pliers, designed in accordance with the present invention;

FIG. 2 is a section along the lines 22 of FIG. 1;

FIG. 3 is a side elevation of the pliers shown in FIG. 1, the pliers being closed and locked;

FIG. 4 is a section along the lines 44 of FIG. 3, shown on an enlarged scale;

FIG. 5 is a side elevation of the pliers illustrated in FIGS. 1 and 7 in open position; and

FIG. 6 is another side elevation of another embodiment, partly in section.

' atent G 'comes into action.

Referring now to the drawings, and in particular to FIGS. 1 to 5, a jaw 2 is secured to the forward end of a rigid arm '1. A supporting member 4 for the movable jaw 5 is hinged at the pin 3 on the rigid arm 1. A handle 7, forming a toggle lever pair together with a lever-8, is pivoted by the pin 6 to the supporting member 4. The handle 7 and the lever 8 are connected with each other in a toggle lever joint 9. The lever 8 projects somewhat beyond the joint 9 and is provided with a set screw 11 on the projecting part 10. The set screw 11 rests against the inside face of the handle 7 and determines the angle of operation of the toggle lever pair 7, 8 and, thus, the gripping power, when closing the pliers.

The rear part of the rigid arm 1 forms a guide on which a brake member is in sliding engagement. The brake member is rigidly fixed to an intermediate member having a joint 15 in which the free end of the toggle-lever 8 is pivoted. A tension spring 16 connects the brake member with the rigid arm 1. The spring 16 may, however, be alternatively fastened, selectively, to the movable jaw 5.

The guide bore in the clamping sleeve is formed in such manner that the sleeve can be retracted on the guide, in the direction of the arrow, against the action of the spring 16. sleeve is transmitted to the movable jaw 5, so that the mouth of the pliers is opened to seize the workpiece. If now the sleeve is released, the spring 16 comes into action and causes the toggle lever 8 and its set screw 11 to rest against the handle 7. At the same time, the sleeve is tilted into its locking position on the guide.

When the handle 7 is then transferred from the position shown in FIG. 1 into the position disclosed in FIG. 3, i.e. when the pliers reach the locking position, the toggle lever pair is in stretchedposition in which the toggle lever The clamping sleeve is locked on its guide, and the jaws 2 and 5 close according to the closing pressure, as predetermined by the set screw 11.

If the grip of the pliers has to be released, the toggle I lever pair 7, 8 must be pushed out of its stretched position. This is being done by means of a lever 19 which is hinged by the pin 20 on the handle 7 and which is forced, against the action of a spring 21, out of its rest position in which it rests on the lever part 8. When the lever 19 is moved into a position spaced apart from the handle 7, the latter and the lever 8 return into their position shown in FIG. 1.

A preferred embodiment of the pliers is illustrated in FIGS. 1 to 5. In this embodiment, the guide on the arm 1 is formed of a bar 22, operating as a guide, which is provided with lateral guide surfaces 23 inclined relative to each other (FIG. 4). A sleeve 24 is arranged on this guide 22 which has a guide bore 25, corresponding to the wedge shape of the guide 22 and having inclined pressure surfaces 26:" As can be seen from FIG. 3, the guide bore 25 widens towards the handle 27.

Since the surfaces 26 and 23 are inclined, they are pressed against each other when the sleeve is locked. Surface contact is obtained between the slide 24 and the guide 22, so that wear of the different co-operating parts of the pliers is reduced to a minimum with the result that in case of wear on the surfaces 23 and 26 the locking action is not affected.

To enable the sleeve 24 to be retracted on its guide 22, as mentioned above, the sleeve 24 is provided with a projection 28 (FIG. 4) at its side.

The embodiment disclosed in FIG. 6 is provided with a cylindrical guide pin 41 in the rigid arm 1, and a locking device 42 is slidably arranged on the pin 41. The locking device 42 is hinged on the toggle lever part 8. A bus-hing 43 is displaceable on the pin 41 in front of the According to FIG. 3, this motion of the locking device 42 and provided with a handle 44 which projects through a slot 45 provided in the arm 1. A compression spring 46 forces the locking device into its end position. To open the pliers, the handle 44 and thus the bushing 43 is retracted and the locking device moved out of its locking position. The locking device opens the jaws by means of the toggle levers. When, during the closing movement of the pliers, the toggle levers reach their stretched position, the locking device is tilted on its guide 41 and locked.

While we have disclosed several embodiments of the present invention, it is to be understood that these embodiment-s are given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claims.

We claim:

1. In a pair of pliers, the combination of an elongated, rigid arm provided at one end with a stationary jaw and at the other end with a handle, a coacting movable jaw pivoted to said arm, a second handle pivoted to said movable jaw, a toggle lever pivotally attached to said second handle and extending away from said jaws and toward said rigid arm, said rigid arm including a guide bar, a slide movably mounted along and in axial direction of said guide bar, said slide tilting and locking against movement away from the jaws, resilient means urging said slide toward said stationary jaw and biasing said movable jaw toward said stationary jaw, and means pivotally connecting said toggle lever to said slide.

2. The pair of pliers, as set forth in claim 1, wherein said resilient means comprises a pull spring, one end of said spring being secured to said slide and the other end of said spring being secured to said rigid arm.

3. The pair of pliers, as set forth in claim 1, wherein said resilient means comprises a pull spring, one end of said spring being secured to said slide and the other end of said spring being secured to said movable jaw.

4. The pair of pliers, as set forth in claim 1, wherein said toggle lever forms an extension beyond the pivot point between said second handle and said toggle lever, a

set screw adjustably inserted in said extension and constituting abutment means for the inside face of said second handle in order to limit the angle between the latter and said toggle lever.

5. The pair of pliers, as set forth in claim 1, wherein said guide bar has inclined, lateral guide faces to form a wedge and said slide has a guide bore of a cross-section complementary to that of said guide bar, and forming pressure surfaces to cooperate with the corresponding inclined, lateral guide faces of said guide bar.

6. The pair of pliers, as set forth in claim 1, wherein said guide bar extends from the rear end of said rigid arm and includes a handle member disposed at the rear end thereof.

7. The pair of pliers, as set forth in claim 1, wherein said guide bar is received in the rear portion of said rigid arm, and said resilient means comprises a helical spring, one end of said spring abutting a rear portion of said guide bar and the other end abutting the rear face of said slide.

8. The pair of pliers, as set forth in claim 7, which includes a bushing axially movably mounted on said guide bar in front of said slide, said rigid arm having a longitudinal slot, said bushing including a handle projecting upwardly from said bushing through said slot of said rigid arm, the axial movement of said bushing and thereby of said slide, bringing about an opening of said aws.

References Cited in the file of this patent UNITED STATES PATENTS 2,499,201 Thayer Feb. 28, 1950 2,519,973 Mead Aug. 22, 1950 2,531,285 Manspeaker Nov. 21, 1950 2,595,579 Hawkins May 6, 1952 2,685,218 Burns Aug. 3, 1954 2,705,899 Beger Apr. 12, 1955 2,751,801 Hostetter June 26, 1956 2,940,345 Farina June 14, 1960 

